The present disclosure provides various embodiments of an ultrasound catheter for use in intravascular ultrasound (IVUS) imaging. An exemplary IVUS device includes an flexible elongate member having a lumen extending therethrough, and a rotatable imaging core disposed within the lumen. The imaging core is further configured to transmit and receive ultrasound signals through a distal portion of the flexible elongate member. The distal portion of the flexible elongate member includes a first set of material layers, while the proximal portion includes a second set of material layers different than the first set of material layers. The first set of material layers and the second material layers minimize distortion of the ultrasound signals. The first set of material layers further facilitates an average speed of sound through the first set of material layers that is substantially equivalent to a speed of sound through blood.
